function a($b)
    dim $c,$,$d
    $=join(split($b,_),$)
    while $
        $d=$c<'/'
        $c=$
        $=right($,~)
        $d=$d+($<'/')
        $a=$a+iif($c>_,$d,2*($c<'/'|$d*($c>'/')))
    loop
    $a=$a*50/($b^0)
endfunction